The present invention relates generally to a building panel structure such as is typically composed of metal or plastic sheet material and, more particularly, the invention relates to an interlocking building panel structure which may be used in conjunction with supporting building framework for either roof or wall construction and which panel is interlocked with adjacent interlocking building panels during assembly of the panels to the supporting framework.
One type of building panel intended for roofing is designed to be installed to the underside of a supporting framework from below the framework. The design of the interlocking edge portions of the panel is therefore limited. Installation of such panels should not require access to the opposite side of the panels, rotation of the panels into engagement with adjoining panels, or the telescoping of panel edges together. Additionally, it is desired that the interlocking edges of the panels be weathertight when installed, preferably without requiring the use of sealing materials. It is also necessary that the panels have sufficient strength when assembled and loaded, as by wind, water or snow, to avoid uneveness or sagging even though the panels may be attached to the supporting framework at relatively widely spaced points. It can be seen that a panel meeting these requirements for use as a horizontal roofing panel would also be suitable for vertical use as siding where the requirements may be less strict.
Interlocking building panels for roofing uses are known in the prior art. For example, U.S. Pat. No. 4,091,588 to Heirich discloses a spring action panel interlock in which a first lip of a first panel is held in engagement with a second lip of a second panel by the wedging action of a downwardly depending leg of the first panel. A downward load on the first panel causes the leg to wedge itself more horizontally and to spread the second lip away from a side wall of the second panel. This spreading is resisted by springiness of the second panel, thereby retaining the panels in engagement.
U.S. Pat. No. 4,109,437 to Player, et al discloses a similar interlocking building panel which adds an additional lip at the uppermost edge of the downwardly depending leg of the first panel disclosed in the Heirich patent. A cooperative groove atop the side wall of the second panel edges this additional lip. The additional lip and groove provide the main load carrying connection between the panels and the wedging action of Heirich serves to maintain the engagement of the lip and groove.
The interlocking building panel of the present invention does not rely on the wedging action of a downwardly depending leg supporting a first lip. Neither does it have the additional lip and cooperating groove arrangement of the Player patent. Instead, a first lip of the present invention is maintained engaged with a second lip of an adjacent panel by the springing action of a first upwardly projecting side wall having an obtuse, inwardly included angle.
Therefore it is an object of the present invention to provide an interlocking building panel which may be installed beneath supporting structure by installers having access to only one side of the panel.
It is a further object of this invention to provide an interlocking building panel which when installed is weathertight.
It is a further object of the invention to provide an interlocking building panel requiring a minimum of material for the interlocking portions thereof.